Increasingly powerful electronic components, such as computer chips or central processing units (CPUs), produce higher wattages of waste heat, which must be continually removed in order to allow the component to operate efficiently. Generally, one planar surface of such a component is exposed, usually indirectly exposed through a thin cover or “lid,” and heat is extracted by some type of add on cooling assembly that is thermally bonded to the exposed surface. Early on, a relatively simple so called “heat sink,” generally a metal plate with cooling fins, was bonded to the exposed surface of the component, and a fan mounted somewhere on or inside the computer case forced air over the cooling fins and out of the case. This worked sufficiently well until CPUs became more powerful, and liquid cooling became necessary. With liquid cooling, the simple, solid plate of the air system is replaced by a so called cold plate, a low profile, hollow box like structure with a lower surface to which the component is bonded, and a finned or channeled inner volume through which coolant is continually pumped to extract heat that is conducted through the lower surface. The coolant exiting the cold plate runs through a liquid to air heat exchanger, which may be passive, but which generally has air blown across it by a fan.
Early liquid cooling systems were often retro fitted add ons favored by the so called “over clockers” who ran CPUs at unconventionally high speeds, and the air to liquid heat exchanger fan unit was often mounted outside the computer case, and sometimes the liquid pump as well. As production CPUs have begun to approach the same speeds, the liquid pumps, heat exchangers and fan units have generally been designed into the computer case initially, but are still separate components, not particularly compact in their overall configuration, and generally operating essentially independently.